Upward mobility: the idea that, if you work hard enough, you can climb the class ladder. It's part of the American Dream, right? That you can pull yourself up by your bootstraps, that you can make a better life for yourself, that your children and grandchildren will have a better life than you do.

But, the fact is, upward mobility in the U.S. is just not that easy. And, it doesn't happen nearly as much as many American believe.

As part of our The Culture of Class series, we spoke to Economics Professor Steven Haider, of Michigan State University, about why the myth of upward mobility exists and why Americans, in particular, are so apt to believe in it.